This invention relates to portable workbenches, and particularly to such portable workbenches which utilize their workbench tops as a double screw vise for holding a variety of workpieces including irregularly shaped workpieces.
In recent years, various portable workbenches have become popular for home use which are typically described in the U.S. Pat. Nos. 3,615,087 to Hickman, 4,061,323 to Beekenkamp, 4,199,135 to Wohrle et al., and in the co-assigned U.S. Pat. No. 4,231,557 to Blachly et al. All of these portable workbenches include a pair of horizontal tabletop, vise jaw members in which one of the tabletop members is in fixed position and the other is adjustably movable toward and away from the fixed jaw by selective operation of a pair of hand crank-operated vise screws. By turning the vise screws different amounts, the movable vise jaw may be selectively, angularly moved with respect to the fixed vise jaw and objects of irregular shape (i.e., tapered) may be readily clamped by the vise.
Of course, as is readily apparent, when the movable vise jaw is moved angularly with respect to the fixed vise jaw, it becomes necessary to compensate for a change in length between the attachment points between the movable vise jaw and the two vise screws so as to avoid binding.
In the above-noted patents to Hickman and Beekenkamp, this binding is avoided by permitting the vise screws and the movable vise jaw to move laterally a slight distance. In the above-noted Blachly et al patent, this binding movement is prevented by pin-and-slot connections between the vise screws and the movable vise jaw. These pin-and-slot connections allow both side-to-side and angular movement of the movable vise jaw with respect to the vise screws when one of the vise screws is operated (i.e., rotated) an amount different from the other vise screw.
Reference is also made to such prior art patents as Castagna, U.S. Pat. No. 1,716,718, which discloses a chuck for holding work in which both of the jaws of the chuck are movable angularly and toward and away from one another by selective operation of a pair of vise screws. Castagna utilizes a pin-and-slot connection to overcome binding when one of the jaws is moved angularly relative to the other. Thomas, U.S. Pat. No. 985,857, discloses a door sash clamp having two movable clamp bars selectively movable toward and away from one another and angularly with respect to one another by selective operation of a pair of vise screws. The vise screws are connected to the clamping bars of the apparatus by means of swivel nuts and bearings. For permitting angular positioning with respect to one another, apertures are provided in the clamp bars through which the vise screws pass, these apertures being larger than the vise screws so as to permit lateral movement between the guideway for the clamping bars and the clamping bars.
As a further example of prior art double screw vises, reference may be made to a woodworking bench which is a part of the Dominy collection from the late 18th and early 19th century on display at the Henry Francis duPont Winterthur Museum in Wilmington, Del. Still further, reference may be made to A Museum Of Early American Tools by Eric Sloane published by Wilford Funk, Inc. in 1974 which discloses a prior art double screw vise.
While all of the above-noted prior art double screw vises and workbenches permitted angular movement of the movable vise jaw, there has been a need to provide a connection between the vise screws and the movable vise jaw which is of simple and economical construction, which efficiently transfers load or force between the vise screws and the movable vise jaw, and yet which permits the vise screws to be easily rotated even when under load.
As mentioned above, the instant invention is a portable workbench. In the above-noted patent to Hickman, the workbench disclosed therein has foldable or collapsible legs which can be folded so as to aid in transporting and storing the workbench. However, these foldable or collapsible legs are relatively complicated and expensive to manufacture. In the above-noted Beekenkamp patent, a portable workbench is disclosed which is supported by a collapsible stand made of lightweight tubing. This stand consists of two rectangular frames which are rigidly connected together at their centers and which are pivotally movable relative to one another between a folded or closed position in which the rectangular frames are on top of one another and an open position in which the frames assume a generally X-shaped configuration when viewed from their ends. The upper sides of the frame are clipped to the frame of the workbench and the bottoms of the frames bear on the ground.
In the Blachly et al patent, the workbench is supported by means of pipe legs which are socketed in receptacles integrally cast with the workbench frame and which are positively secured to the frame by means of removable fasteners (bolts). While these pipe legs provide an extremely solid support for the workbench, they require the use of threaded fasteners to hold the legs securely in place and a die cast frame for the workbench.
As noted above, certain of the prior art portable workbenches utilize relatively complicated castings for at least some portions of the workbench frame. While these castings result in a highly rigid structure and are aesthetically appealing, they also result in relatively high manufacturing and tooling costs for the workbench.
Among the several objects and features of the present invention may be noted the provision of a portable workbench, such as described above, in which each of the vise screws is positively constrained against substantial lateral and vertical movement and yet in which the movable vise jaw is relatively free, within a limited range, to assume any angular position with respect to the fixed jaw;
The provision of such a portable workbench in which the ends of the vise screws opposite their crank handles are supported by a guide constrained against both lateral and vertical movement;
The provision of such a portable workbench in which the frame of the workbench is fabricated entirely of sheet metal or the like and which is exceedingly rigid without the necessity of using costly castings;
The provision of such a portable workbench in which the vise screws are substantially enclosed within the frame;
The provision of such a portable workbench which is solidly supported at a convenient work height by means of pipe legs which are readily removably secured to the workbench frame without the use of fasteners or without the necessity of utilizing even simple hand tools;
The provision of such a portable workbench which, with its legs removed, may be solidly clamped to a tabletop or the like;
The provision of such a portable workbench which has unobstructed entry under the workbench from all sides thereof to permit convenient use of the workbench;
The provision of such a portable workbench in which the support legs, when removed from the workbench frame, may be stored within the workbench frame; and
The provision of such a portable workbench which is of lightweight but yet rigid and solid construction, which is easy and relatively inexpensive to manufacture, and which is convenient to use.
Other objects and features of this invention will be in part apparent and in part pointed out hereinafter.